Projector and image display method

ABSTRACT

A projector includes: first and second display panels and a projection unit that superposes images formed by the first and second display panels and that projects the superposed images on a projection surface. The first and second display panels are arranged such that the image formed by one display panel is projected to a position shifted by a predetermined distance in at least one of the row direction and column direction of the picture element array with respect to the position where the image formed by the other display panel is projected.

TECHNICAL FIELD

The present invention relates to a projector and an image displaymethod.

BACKGROUND ART

Regarding the development of higher image quality of projectors, thereis increasing demand for higher resolution, to say nothing of brightnessand color reproducibility. In response, technology has been proposedrelating to the higher resolution of a projected image.

For example, Patent Document 1 discloses a projection display devicethat is capable of providing a projected image having twice the numberof pixels as the number of pixels of a display panel.

The projection-type display device described in Patent Document 1 has aliquid crystal panel for display, a projection optical system thatenlarges and projects the image formed on the liquid crystal panel fordisplay on a screen, and shifting means provided between the liquidcrystal panel for display and the projection optical system.

The shifting means is a component that uses the double-refractionphenomenon of a quartz plate to shift the optical path and includes aquartz plate and a liquid crystal panel for controlling the polarizationdirection. The image light from the liquid crystal panel for display isirradiated into the quartz plate by way of the liquid crystal panel forcontrolling the polarization direction.

The liquid crystal panel for controlling polarization direction isprovided for controlling the polarization direction of light that isirradiated into the quartz plate. The optical path of light that isemitted from the quartz plate when the liquid crystal panel forcontrolling the polarization direction is OFF is shifted in apredetermined direction with respect to the optical path of light thatis emitted from the quartz plate when the liquid crystal panel forcontrolling the polarization direction is ON.

An original image having a number of pixels that is twice the number ofpixels of the liquid crystal panel for display is divided into twoimages I1 and I2 at a spacing of one pixel in the horizontal direction,and images I1 and I2 are displayed in time divisions on a liquid crystalpanel for display. The liquid crystal panel for polarization control isturned ON during the display interval of image I1 and the liquid crystalpanel for polarization control is turned OFF during the display intervalof image I2.

The projected image of image I1 and the projected image of image I2 aredisplayed on the screen in time divisions. The projected image of imageI2 is displayed at a position that is shifted by one-half the pixelpitch in the horizontal direction with respect to the projected image ofimage I1. By making the display cycle of images I1 and I2 shorter thanthe afterimage interval of the human eye, an image in which theprojected images of images I1 and I2 are superposed can be observed.This observed image (the superposed image of images I1 and I2) has anumber of pixels that is equivalent to the original image.

Configurations in which an optical path shifting means is providedbetween a liquid crystal panel and projection lens to increase thenumber of pixels of a projected image are also disclosed in PatentDocuments 2 and 3.

LITERATURE OF THE PRIOR ART Patent Documents

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. H04-113308-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 2006-146074-   Patent Document 3: Japanese Unexamined Patent Application    Publication No. H07-104278

DISCLOSURE OF THE INVENTION

Nevertheless, the devices disclosed in Patent Documents 1 to 3 entailthe problems of increased scale and higher costs of the devices due tothe necessity of providing an optical path shifting means.

There is the further problem in which the amount of power consumptionincreases due to the consumption of electric power by the optical pathshifting means.

An object of the present invention is to provide a projector and imagedisplay method that can display a high-precision projected image andsolve the problems described above.

According to one aspect of the present invention for achieving theabove-described object, a projector is provided that includes:

-   first and second display panels that are each equipped with a    plurality of picture elements and that modulate incident light by    means of the plurality of picture elements to form images; and-   projection means that superposes the images that are formed on the    first and second display panels to project the superposed images on    a projection surface;-   wherein the first and second display panels are arranged such that    the image of one of the display panels is projected on a position    that is shifted by a predetermined distance with respect to the    image of the other display panel.

According to another aspect of the present invention, an image displaymethod is provided that is an image display method carried out in aprojector that is provided with first and second display panels that areeach equipped with a plurality of picture elements and that modulateincident light by means of the plurality of picture elements to formimages, and that superposes the images formed by the first and seconddisplay panels to project the superposed images on a projection surface,the method including:

-   arranging the first and second display panels such that the image of    one display panel is projected on a position that is shifted by a    predetermined distance with respect to the image of the other    display panel; and-   forming a first green image on the first display panel, and    alternately forming a second green image, in which at least the    luminance differs from that of the first green image, and a blue    image or red image on the second display panel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing the configuration of a projectoraccording to a first exemplary embodiment of the present invention.

FIG. 2 is a schematic view showing an example of the light source unitof the projector shown in FIG. 1.

FIG. 3 is a schematic view showing an example of the cross-dichroicprism of the projector shown in FIG. 1.

FIG. 4A is a characteristics chart showing the spectral transmissioncharacteristics for S-polarized light of the BR surface of thecross-dichroic prism shown in FIG. 3.

FIG. 4B is a characteristics chart showing the spectral transmissioncharacteristics for P-polarized light of the BR surface of thecross-dichroic prism shown in FIG. 3.

FIG. 4C is a characteristics chart showing the spectral transmissioncharacteristics for S-polarized light of the RR surface of thecross-dichroic prism shown in FIG. 3.

FIG. 4D is a characteristics chart showing the spectral transmissioncharacteristics for P-polarized light of the RR surface of thecross-dichroic prism shown in FIG. 3.

FIG. 5 is a schematic view for describing the relative positionalrelation on the projection surface of the image formation regions of thetwo display panels of the projector shown in FIG. 1.

FIG. 6 is a block diagram showing the configuration of the controlsystem of the projector shown in FIG. 1.

FIG. 7 is a timing chart showing an example of the image formationoperation realized by a display panel of the projector shown in FIG. 1.

FIG. 8 is a timing chart showing another example of the image formationoperation realized by a display panel of the projector shown in FIG. 1.

FIG. 9 is a schematic view showing the configuration of the projectoraccording to the second exemplary embodiment of the present invention.

FIG. 10 is a schematic view showing the phosphor wheel of one lightsource unit of the projector shown in FIG. 9.

FIG. 11 is a schematic view showing the configuration of one lightsource unit of the projector shown in FIG. 9.

FIG. 12 is a schematic view showing the phosphor wheel of another lightsource unit of the projector shown in FIG. 9.

FIG. 13 is a schematic view showing an example of the cross-dichroicprism of the projector shown in FIG. 9.

FIG. 14 is a block diagram showing the configuration of the controlsystem of the projector shown in FIG. 9.

EXPLANATION OF REFERENCE NUMBERS

-   11-14 light source unit-   101, 102 dichroic mirror-   103-105 polarization beam splitter-   106-108 display panel-   109 cross-dichroic mirror-   110 projection lens

MODE FOR CARRYING OUT THE INVENTION

Exemplary embodiments of the present invention are next described withreference to the accompanying drawings.

First Exemplary Embodiment

FIG. 1 is a schematic view showing the configuration of the projectoraccording to the first exemplary embodiment of the present invention.

Referring to FIG. 1, the projector is what is known as a three-panelprojector that uses three display panels and that includes: light sourceunits 11-14, dichroic mirrors 101 and 102, polarization beam splitters103-105, display panels 106-108, cross-dichroic mirror 109, andprojection lens 110.

Light source units 11 and 14 are each equipped with a green solid-statelight source that supplies green light having its peak wavelength in thegreen wavelength band (for example, an LED or semiconductor laser inwhich the emitted light color is green) and are configured such that theoutput light of this green solid-state light source is emitted asparallel light flux.

Light source units 11 and 14 are of the same configuration (the emittedlight wavelengths are the same) and the actual configuration istherefore here described taking light source unit 11 as an example.

FIG. 2 shows an example of light source unit 11. As shown in FIG. 2,light source unit 11 includes LED light source 201, collimator lenses202 and 203, polarization conversion unit 204, and lens 205.

LED light source 201 emits green light. With the trend to larger sizesof light-emitting elements in recent years, high-currenthigh-light-output LED light sources that can be driven at several tensof amperes are available, and such a light source may be used as LEDlight source 201.

Collimator lenses 202 and 203 are components for converting the outputlight of LED light source 201 to parallel light flux. In addition, theshape, size, and number of lenses of the collimator lenses can bealtered as appropriate.

The output light of LED light source 201 is irradiated into polarizationconversion unit 204 by way of collimator lenses 202 and 203. The outputlight of LED light source 201 is unpolarized light, and polarizationconversion unit 204 adjusts the unpolarized light from LED light source201 to P-polarized light or S-polarized light that is linearly polarizedlight. For example, a configuration that combines a polarization beamsplitter array and retardation plate can be used as polarizationconversion unit 204. The light can be adjusted to any polarization ofP-polarization and S-polarization by the selection of the polarizationbeam splitter and the retardation plate.

Lens 205 makes up at least a portion of the optical system thatirradiates the light from polarization conversion unit 204 to displaypanel 106.

Light source unit 12 is provided with a red solid-state light sourcethat supplies red light having its peak wavelength in the red wavelengthband (for example, an LED or semiconductor laser in which the emittedlight color is red) and is configured such that the output light of thissolid-state light source is emitted as parallel light flux.

Light source unit 13 is provided with a blue solid-state light sourcethat supplies blue light having its peak wavelength in the bluewavelength band (for example, an LED or semiconductor laser in which thecolor of emitted light is blue) and is configured such that the outputlight of this blue solid-state light source is emitted as parallel lightflux.

With the exception that the emitted light colors of the LED lightsources differ, light source units 12 and 13 are made up of a unitconfiguration such as shown in FIG. 2. A light source highcurrent-high-light output red LED and blue LED can be used as the LEDlight sources.

In the present exemplary embodiment, green light (S-polarized light) isemitted from light source unit 11, green light (P-polarized light) isemitted from light source unit 14, red light (P-polarized light) isemitted from light source unit 12, and blue light (P-polarized light) isemitted from light source unit 13.

The optical axis of light source unit 11 and the optical axis of lightsource unit 12 are orthogonal, and dichroic mirror 101 is arranged atthe intersection of these optical axes. Dichroic mirror 101 has theproperty of transmitting green light and red light. This dichroic mirror101 may be omitted.

The green light (S-polarized light) from light source unit 11 istransmitted by dichroic mirror 101 and irradiated into polarization beamsplitter 103.

Polarization beam splitter 103 has the property of transmittingP-polarized light and reflecting S-polarized light. The green light(S-polarized light) from light source unit 11 is thus reflected in thedirection of display panel 106 by polarization beam splitter 103. Thegreen light (S-polarized light) that is reflected by polarization beamsplitter 103 is irradiated into display panel 106.

The red light (P-polarized light) from light source unit 12 istransmitted through dichroic mirror 101 and irradiated into polarizationbeam splitter 104.

Polarization beam splitter 104 has the property of transmittingP-polarized light and reflecting S-polarized light. The red light(P-polarized light) from light source unit 12 is thus transmittedthrough polarization beam splitter 104 and irradiated into display panel107.

The optical axis of light source unit 13 and the optical axis of lightsource unit 14 are orthogonal, and dichroic mirror 102 is arranged atthe intersection of these optical axes. Dichroic mirror 102 has theproperty of reflecting blue light and transmitting green light.

The blue light (P-polarized light) from light source unit 13 isreflected in the direction of polarization beam splitter 105 by dichroicmirror 102. On the other hand, the green light (P-polarized light) fromlight source unit 14 is transmitted through dichroic mirror 102 andirradiated into polarization beam splitter 105.

Polarization beam splitter 105 has the property of transmittingP-polarized light and reflecting S-polarized light. The blue light(P-polarized light) from light source unit 13 and the green light(P-polarized light) from light source unit 14 are each transmittedthrough polarization beam splitter 105 and irradiated into display panel108.

Display panels 106-108 are reflective liquid crystal panels of whichLiquid Crystal on Silicon (LCoS) is representative.

Display panel 106 spatially modulates the green light (S-polarizedlight) from light source unit 11 to form a green image. This green imageis formed from reflected light (P-polarized light) from display panel106. The reflected light (P-polarized light) from display panel 106 istransmitted through polarization beam splitter and irradiated intocross-dichroic prism 109.

Display panel 107 spatially modulates the red light (P-polarized light)from light source unit 12 to form a red image. This red image is made upof the reflected light (S-polarized light) from display panel 107.

The reflected light (S-polarized light) from display panel 107 isreflected in the direction of cross-dichroic prism 109 by polarizationbeam splitter 104.

Display panel 108 spatially modulates the blue light (P-polarized light)from light source unit 13 to form a blue image and spatially modulatesthe green light (P-polarized light) from light source unit 14 to form agreen image. The blue image and green image are formed in timedivisions, and both images are made up of the reflected light(S-polarized light) from display panel 108.

The reflected light (S-polarized light) from display panel 108 isreflected in the direction of cross-dichroic prism 109 by polarizationbeam splitter 105.

Cross-dichroic prism 109 combines the image light from display panels106-108.

FIG. 3 is a schematic view showing an example of cross-dichroic prism109.

As shown in FIG. 3, cross-dichroic prism 109 includes four right-angleprisms 109 a-109 d. Each of right-angle prisms 109 a-109 d includes: thefirst and second surfaces that constitute the sides that form the rightangle of the triangle of the base; and a third surface that constitutesthe hypotenuse of the triangle.

The first surface of right-angle prism 109 a is joined to the secondsurface of right-angle prism 109 b, and the second surface ofright-angle prism 109 a is joined to the first surface of right-angleprism 109 c. The first surface of right-angle prism 109 d is joined tothe second surface of right-angle prism 109 c, and the second surface ofright-angle prism 109 d is joined to the first surface of right-angleprism 109 b.

A uniform surface is formed by the joined surfaces of the first surfaceof right-angle prism 109 a and the second surface of right-angle prism109 b and the joined surfaces of the first surface of right-angle prism109 d and the second surface of right-angle prism 109 c, and the RRsurface is formed on this surface.

A uniform surface is formed by the joined surfaces of the second surfaceof right-angle prism 109 a and the first surface of right-angle prism109 b and the joined surfaces of the first surface of right-angle prism109 c and the second surface of right-angle prism 109 d, and the BRsurface is formed on this surface.

FIG. 4A shows the spectral transmission characteristics of the BRsurface for S-polarized light. FIG. 4B shows the spectral transmissioncharacteristics of the BR surface for P-polarized light. In FIGS. 4A and4B, the horizontal axis shows the wavelength (nm) and the vertical axisshows the transmittance (%).

As shown in FIG. 4A, for S-polarized light, the BR surface has theproperty of reflecting light of the blue and green wavelength bands andtransmitting light of the red wavelength band. Further, as shown in FIG.4B, for P-polarized light, the BR surface has the property of reflectinglight of the blue wavelength band and transmitting light of otherwavelength bands (including the green and red wavelength bands). Bymeans of these properties of FIGS. 4A and 4B, green light (P-polarizedlight) and red light (S-polarized light) are transmitted through the BRsurface and blue light (S-polarized light) and green light (S-polarizedlight) are reflected by the BR surface.

FIG. 4C shows the spectral transmission characteristics for S-polarizedlight of the RR surface. FIG. 4D shows the spectral transmissioncharacteristics of the RR surface for P-polarized light. In FIGS. 4C and4D, the horizontal axis shows wavelength (nm) and the vertical axisshows the transmittance factor (%).

As shown in FIG. 4C, for S-polarized light, the RR surface has theproperty of transmitting light of the blue and green wavelength bandsand reflecting light of the red wavelength band. In addition, as shownin FIG. 4D, for P-polarized light, the RR surface has the property ofreflecting light of the red wavelength band and transmitting light ofother wavelength bands (including the green and blue wavelength bands).In accordance with these characteristics of FIGS. 4C and 4D, green light(P-polarized light and S-polarized light) and blue light (S-polarizedlight) are transmitted through the RR surface and red light (S-polarizedlight) is reflected by the RR surface.

In cross-dichroic prism 109 shown in FIG. 3, the third surface of eachof right-angle prisms 109 a-109 c is assumed to be the first, second,and third incident surfaces, respectively, and the third surface ofright-angle prism 109 d is assumed to be the emission surface.

Green light (P-polarized light) from display panel 106 is irradiatedfrom the first incident surface, red light (S-polarized light) fromdisplay panel 107 is irradiated from the second incident surface, andblue light (S-polarized light) and green light (S-polarized light) fromdisplay panel 108 are irradiated from the third incident surface.

The green light (P-polarized light) that was irradiated from the firstincident surface is transmitted through the BR surface and the RRsurface and is emitted from the emission surface. The red light(S-polarized light) that was irradiated from the second incident surfaceis reflected by the RR surface and then emitted from the emissionsurface. The blue light (S-polarized light) and green light (S-polarizedlight) that were irradiated from the third incident surface arereflected by the BR surface and then emitted from the emission surface.

Projection lens 110 is arranged on the emission surface side ofcross-dichroic prism 109. Projection lens 110 enlarges and projects theimages that are formed by display panels 106-108 on the projectionsurface.

Each of display panels 106-108 is provided with an image formationregion in which is formed an image composed of a plurality of pictureelements. The number of picture elements and picture element size ofdisplay panels 106-108 are the same. However, the relative positionalrelation of the image formation regions on the projection surfacediffers for display panel 108 and display panels 106 and 107.

For example, on the projection surface, the image formation region ofdisplay panel 108 is projected on a position that is shifted by apredetermined amount in the horizontal direction (the direction of thepicture element rows), the vertical direction (the direction of thepicture element columns), or in both directions with respect to theprojection position of the image formation region of display panel 106.Display panel 107 is arranged such that the projection position of itsimage formation region coincides with the projection position of theimage formation region of display panel 106. The perpendicular line thatpasses through the center of the image formation region of display panel108 and the perpendicular line that passes through the center of theimage formation region of display panel 106 do not lie on the sameplane. On the other hand, the perpendicular line that passes through thecenter of the image formation region of display panel 106 and theperpendicular line that passes through the center of the image formationregion of display panel 107 lie on the same plane. In these cases, thecenter of an image formation region is also the intersection of thediagonal lines of the image formation region. Together with this, thecenter ray (optical axis) of each of luminous flux from light sourceunit 11 and light source unit 12 and the center ray (optical axis) ofeach of luminous flux from light source unit 13 and light source unit 14do not lie in the same plane.

FIG. 5 gives a schematic representation of the relative positionalrelation of the image formation regions of display panels 106 and 108 onthe projection surface.

As shown in FIG. 5, picture element 108 a of the projected image ofdisplay panel 108 is shifted by 0.5 picture elements (indicating 0.5times the picture element pitch) in each of the row direction and columndirection with respect to picture element 106 a of the projected imageof display panel 106 that corresponds to picture element 108 a.

In the present exemplary embodiment, a panel arrangement that shifts thecorresponding picture element of an image that is projected on theprojection surface between display panel 108 and display panel 106 isused to increase the number of picture elements of the observed imagewhen the projected image is viewed.

More specifically, a green image is formed on display panel 106, a redimage is formed on display panel 107, and a blue image and a green imageare formed in time divisions on display panel 108. On the projectionsurface, the green image that is formed on display panel 108 isprojected to a position that is shifted by 0.5 picture elements in eachof the row direction and column direction with respect to the projectedposition of the green image that is formed on display panel 106. Due tothe afterimage phenomenon of the human eye, an image is observed inwhich these green images are spatially or temporally blended (asuperposed image). The number of picture elements of this observed imageis approximately four times the number of picture elements of each ofdisplay panels 106 and 108.

Human vision typically has a high spatial frequency characteristic forluminance but has a relatively low characteristic for hue or saturation,and the contribution of green to the luminance component is greater thanthat of red and blue. Accordingly, higher resolution of the observedimage (superposed image) of the images (red, blue and green) formed bydisplay panels 106-108 can be achieved by increasing the number ofpicture elements only for the green image.

The configuration and operation of the control system of the projectorof the present exemplary embodiment are next described in detail.

FIG. 6 shows an example of the control system of the projector.Referring to FIG. 6, the projector is equipped with light source driveunit 2 that drives light source units 11-14, panel drive unit 3 thatdrives display panels 106-108, input unit 4 that is provided with, forexample, buttons or keys for operation that supply instruction signalsaccording to the input operation of the user, and control unit 1 thatreceives the instruction signals from input unit 4 to control theoperation of light source drive unit 2 and panel drive unit 3.

Control unit 1 both supplies drive timing signal S2 for driving each ofdisplay panels 106-108 to panel drive unit 3 and supplies lightingtiming signal S3 for driving each of light source units 11-14 to lightsource drive unit 2.

Panel drive unit 3 individually drives display panels 106-108 based onvideo signal Si applied as input from an outside device and drive timingsignal S2 from control unit 1. In this case, the outside device is, forexample, an information processing device such as a personal computer oran image apparatus such as a recorder.

More specifically, based on video signal S1 and drive timing signal S2,panel drive unit 3 generates image signal S21 that indicates a firstgreen image, image signal S22 that indicates a red image, image signalS23 that indicates a blue image, and image signal S24 that indicates asecond green image. The first green image that is based on image signalS21 is then formed on display panel 106, the red image that is based onimage signal S22 is formed on display panel 107, and the blue image thatis based on image signal S23 and the second green signal that is basedon image signal S24 are formed in time divisions on display panel 106.

Light source drive unit 2 individually controls the lighted states oflight source units 11-14 in accordance with lighting timing signal S3from control unit 1.

More specifically, light source drive unit 2 generates lighting signalS31 that instructs lighting/extinguishing of light source unit 11,lighting signal S32 that instructs the lighting/extinguishing of lightsource unit 12, lighting signal S33 that indicates thelighting/extinguishing of light source unit 13, and lighting signal S34that instructs the lighting/extinguishing of light source unit 14. Thelighting operation of light source units 11-14 is controlled inaccordance with these lighting signals S31-S34.

FIG. 7 is a timing chart showing an example of image signals S21-S24 andlighting signals S31-S34.

Referring to FIG. 7, of the interval of one frame, light source units11,12, and 14 are each assumed to be set to the ON state and lightsource unit 13 is assumed to be set to the OFF state in the interval T1from time t1 (the starting point of the frame) until time t2. The firstgreen image that is based on image signal S21 is then formed by displaypanel 106, the red image that is based on image signal S22 is formed bydisplay panel 107, and the second green image that is based on imagesignal S24 is formed by display panel 108.

In interval T2 from time t2 until time t3 (the end time of the frame),light source units 11, 12, and 13 are each set to the ON state and lightsource unit 14 is set to the OFF state. The first green image that isbased on image signal S21 is then formed by display panel 106, the redimage that is based on image signal S22 is formed by display panel 107,and the blue image that is based on image signal S23 is formed bydisplay panel 108.

According to the operation shown in FIG. 7, in interval T1, the firstgreen image that is formed on display panel 106, the red image that isformed on display panel 107, and the second green image that is formedon display panel 108 are each projected by projection lens 110. In thiscase, a first superposed image in which the first green image, the redimage, and the second green image are superposed is displayed on theprojection surface.

In interval T2, the first green image that is formed on display panel106, the red image that is formed on display panel 107, and the blueimage that is formed on display panel 108 are each projected byprojection lens 110. In this case, a second superposed image in whichthe first green image, the red image, and the blue image are superposedis displayed on the projection surface.

The user, due to the afterimage phenomenon, sees an image in which thefirst superposed image displayed in interval T1 and the secondsuperposed image displayed in interval T2 are temporally blended. Inthis observed image, the second green image is shifted by 0.5 pictureelements in the row direction and the column direction with respect tothe first green image. As a result, the number of picture elements ofthe superposed image of the first and second green images isapproximately four times the number of picture elements of each ofdisplay panels 106 and 108.

Due to the above-described characteristic of human visual perception,increasing the number of picture elements of the green image causes anapparent increase in the number of picture elements of the observedimage. As a result, a higher resolution of the observed image can beachieved.

FIG. 8 is a timing chart that shows another example of image signalsS21-S24 and lighting signals S31-S34.

Referring to FIG. 8, in interval T1, light source units 11, 12, and 14are each set to the ON state and light source unit 13 is set to the OFFstate. The first green image that is based on image signal S21 is thenformed on display panel 106, the red image that is based on image signalS22 is formed on display panel 107, and the second green image that isbased on image signal S24 is formed on display panel 108.

In interval T2, light source units 12 and 13 are each set to the ONstate, and light source units 11 and 14 are each set to the OFF state.The red image that is based on image signal S22 is then formed ondisplay panel 107, and the blue image that is based on image signal S23is formed on display panel 108.

According to the operation shown in FIG. 8, in interval T1, the firstgreen image that is formed on display panel 106, the red image that isformed on display panel 107, and the second green image that is formedon display panel 108 are each projected by projection lens 110. In thiscase, a first superposed image in which the first green image, the redimage, and the second green image are superposed is displayed on theprojection surface.

In interval T2, the red image that is formed on display panel 107 andthe blue image that is formed on display panel 108 are each projected byprojection lens 110. In this case, a second superposed image in whichthe red image and the blue image are superposed is displayed on theprojection surface.

Due to the afterimage phenomenon, the user observes an image in whichthe first superposed image displayed in interval T1 and the secondsuperposed image displayed in interval T2 are temporally blended. Inthis observed image, the second green image is shifted by 0.5 pictureelements in the row direction and column direction with respect to thefirst green image. As a result, the number of picture elements of thesuperposed image of the first and second green images is approximatelyfour times the number of picture elements of each of display panels 106and 108.

Due to the above-described characteristic of human visual perception,the increase of the number of picture elements of the green imageresults in an increase of the apparent number of picture elements of theobserved image itself, whereby higher resolution of the observed imagecan be achieved.

In the operations shown in FIGS. 7 and 8, intervals T1 and T2 can be setas appropriate taking into consideration the response characteristic ofthe display panels and the display period in which images can be blendedbased on the afterimage phenomenon of the human eye.

In addition, in order to reliably increase the number of pictureelements of the observed image by the picture element shift, panel driveunit 3 may generate image signals S21 and S24 such that the content (forexample, the luminance value) of the first green image and the secondgreen image is different.

For example, in a case in which video signal Si includes video signalsR, G, and B that indicate images R, G, and B of resolution of 3840(horizontal)×2160 (vertical), display panels 106-108 are each assumed tobe panels having a resolution of 1920 (horizontal)×1080 (vertical).Panel drive unit 3 resolves image G of video signal G into a first imagecomposed of odd-numbered lines and a second image composed ofeven-numbered lines. Panel drive unit 3 then generates image G1 in whichpicture elements are deleted in every other picture element in thehorizontal direction for the first image and generates image signal S21that indicates image G1. Panel drive unit 3 further generates image G2in which picture elements are deleted in every other picture element inthe horizontal direction for the second image and generates image signalS24 for the second image. Each of images G1 and G2 is an image having aresolution of 1920 (horizontal)×1080 (vertical).

No particular limitations are imposed on the above-described method ofgenerating image signals S21 and 24. Image signals S21 and S24 may begenerated by any method as long as the effect of increasing the numberof picture elements by picture element shifting is obtained.

For video signals R and B, panel drive unit 3 implements a process ofconverting images R and B of a resolution of 3840 (horizontal)×2160(vertical) to images R and B having a resolution of 1920(horizontal)×1080 (vertical). A well-known resolution conversion methodsuch as deleting picture elements can be applied as this process. Paneldrive unit 3 then generates image signals S22 and S23 that indicateimages R and B, respectively, and that have a resolution of 1920(horizontal)×1080 (vertical).

The projector of the present exemplary embodiment described hereinaboveexhibits the following action and effects.

In a known three-panel projector, display panel 108 displays only a blueimage. In the present exemplary embodiment, display panel 108 isconfigured to display a blue image and a green image in time divisions,and further, this display panel 108 and display panel 106 that displaysa green image are arranged with respect to projection lens 110 such thatone projected image is shifted by a predetermined amount in thedirection of alignment of picture elements with respect to the otherprojected image, whereby the number of picture elements of the greenimage is increased to thereby have the effect of increasing the numberof picture elements of the observed image.

The two main points of alteration from a known three-panel projector arealteration of the arrangement of display panels and alteration of theimage formation operation in the display panels, and provision of a newconstituent element such as an optical path shifting means is thereforenot necessary. As a result, increase in the size of the device, cost andpower consumption can all be reduced.

Second Exemplary Embodiment

FIG. 9 is a schematic view showing the configuration of the projectoraccording to the second exemplary embodiment of the present invention.

Referring to FIG. 9, the projector includes: light source units 61 and62, dichroic mirror 601, TIR (Total Internal Reflection) prisms 602-604,digital micromirror devices (DMDs) 605-607, cross-dichroic prism 608,retardation plate 609, and projection lens 610.

Light source unit 61 supplies yellow light (that includes a greencomponent and a red component). Light source unit 61 is provided with,for example, phosphor wheel 611 as shown in FIG. 10. Region 613, inwhich a yellow phosphor is applied that emits yellow light in responseto the irradiation of excitation light (laser light), is formed onphosphor wheel 611 along the circumferential direction.

FIG. 11 shows an example of light source unit 61. Referring to FIG. 11,light source unit 61 includes laser 701 for excitation, condensinglenses 702 and 703, dichroic mirror 704, polarization conversion unit705, and lens 706.

Laser 701 is a blue laser with an oscillation wavelength of, forexample, 460 nm. The oscillation wavelength of laser 701 is not limitedto 460 nm. Laser 701 may use a laser of any wavelength as long as thelaser is capable of exciting the yellow phosphor.

The laser light that is emitted from laser 701 is irradiated intodichroic mirror 704. Dichroic mirror 704 has the property of reflectinglight of 460 nm and transmitting light of the yellow wavelength band(including the green and red wavelength bands). Dichroic mirror 704reflects the laser light from laser 701 toward phosphor wheel 611.

The laser light from dichroic mirror 704 passes by way of condensinglenses 702 and 703 and is irradiated upon region 613 of phosphor wheel611 in which the yellow phosphor has been applied. In region 613, theyellow phosphor is excited by the laser light and yellow fluorescentlight is emitted.

The yellow fluorescent light that is emitted from region 613 passesthrough condensing lenses 702 and 703 and dichroic mirror 704 and isirradiated into polarization conversion unit 705.

Polarization conversion unit 705 adjusts the incident light fromdichroic mirror 704 to P-polarized light or S-polarized light.Polarization conversion unit 705 is similar to polarization conversionunit 204 shown in FIG. 2 and, for example, by the selection of apolarization beam splitter and retardation plate, is capable ofadjusting to either polarization of P-polarization and S-polarization.

Lens 706 constitutes a portion of the optical system that irradiates thelight from polarization conversion unit 705 to DMDs 605 and 606.

Light source unit 61 supplies blue light and green light in timedivisions. The basic configuration of light source unit 61 issubstantially the same as light source unit 62, but the configurationdiffers regarding, for example, the phosphor wheel or the laser lightsource.

Light source unit 62 is provided with phosphor wheel 612 as shown inFIG. 12. In phosphor wheel 612, region 614 to which a green phosphor isapplied that emits green fluorescent light in response to theirradiation of blue light (laser light) that is the excitation light andregion 615 through which blue light (laser light) is transmitted areformed in the circumferential direction. Regions 614 and 615 are formedat a predetermined ratio in the circumferential direction. The numberand ratio of regions 614 and 615 can be set as appropriate.

The unit configuration shown in FIG. 11 can be applied in light sourceunit 62. For example, in the unit shown in FIG. 11, dichroic mirror 704is omitted and phosphor wheel 611 replaced by phosphor wheel 612. Stillfurther, a set of condensing lenses 702 and 703 is further prepared anda laser having its peak wavelength in the blue wavelength band is usedas laser 701. This set and laser 701 are arranged so as to face thesurface of phosphor wheel 612 on the side opposite to the side on whichlens 705 is arranged. Phosphor wheel 612 is rotated and the blue laserlight from laser light 701 is condensed on phosphor wheel 612 bycondensing lenses 702 and 703.

In region 614 of phosphor wheel 612, green fluorescent light is emittedfrom the phosphor that is excited by blue laser light. The greenfluorescent light (emitted luminous flux) that is radiated from thesurface of region 614 on the side opposite to laser 701 is converted toparallel luminous flux by condensing lenses 702 and 703, and afterhaving been adjusted to one polarization by polarization conversion unit204, is emitted from lens 706.

In region 615 of phosphor wheel 612, the blue laser light istransmitted, whereby blue laser light (diffused light) is emitted fromthe surface of region 615 that is on the side opposite to laser 701. Theblue laser light (diffused light) that is emitted from region 615 isconverted to parallel luminous flux by condensing lenses 702 and 703,and after having been adjusted to one polarization by polarizationconversion unit 204, is emitted from lens 706.

Lens 706 makes up a portion of the optical system that directs the lightfrom polarization conversion unit 705 toward DMD 607.

By means of the above-described configuration, when phosphor wheel 612is rotated at a predetermined speed, blue light and green light fromlight source unit 62 are alternately emitted.

In the present exemplary embodiment, yellow light (S-polarized light) isemitted from light source unit 61, and green light (P-polarized light)and blue light (P-polarized light) are alternately emitted from lightsource unit 62.

The yellow light (S-polarized light) that is emitted from light sourceunit 61 is irradiated into dichroic mirror 601. The yellow lightcontains a red component and a green component, and dichroic mirror 601has the characteristic of transmitting light of the red component andreflecting light of the green component.

The red light that is transmitted through dichroic mirror 601 isirradiated into TIR prism 603 by way of retardation plate 609. Red light(P-polarized light) is irradiated into TIR prism 603 by way ofretardation plate 609.

TIR prism 603 is a total reflection prism assembly that is composed offirst and second right-angle prisms and in which a total reflectionsurface is provided. The first and second right-angle prisms each havefirst and second surfaces that make up the sides that form the rightangle of a triangle and a third surface that forms the hypotenuse of thetriangle and are arranged such that the third surfaces face each other.

The first surface of the first right-angle prism is the incident surfaceof TIR prism 603, and DMD 606 is arranged to face the second surface ofthe first right-angle prism. The second surface of the secondright-angle prism is the emission surface of TIR prism 603.

The red light that is irradiated from retardation plate 609 to TIR prism603 is totally reflected by the internal total reflection surfaces andis emitted from the second surface of the first right-angle prism. Thelight that is emitted from this second surface is irradiated into DMD606.

DMD 606 is a display panel and includes a plurality of micromirrors.Each micromirror is configured to change its angle according to a drivevoltage, the reflection angle differing for a case in which a drivevoltage that indicates the ON state is supplied and a case in which adrive voltage that indicates the OFF state is supplied. Through theON/OFF control of each micromirror according to an image signal, theincident luminous flux is spatially modulated to form an image.

A red image is formed by the reflected light (S-polarized light) fromDMD 606. The red light (S-polarized light) from DMD 606 passes throughTIR prism 603 and is irradiated into cross-dichroic prism 608.

The green light (S-polarized light) that is reflected by dichroic mirror601 is irradiated into TIR prism 602. TIR prism 602 also has the sameconfiguration as TIR prism 603.

The green light that is irradiated from dichroic mirror 601 into TIRprism 602 is totally reflected by the internal total reflection surfacesand is emitted from the second surface of the first right-angle prism.The light that is emitted from this second surface is irradiated intoDMD 605.

DMD 605 also has the same configuration as DMD 606. A green image isformed by the reflected light (P-polarized light) from DMD 605. Thegreen light (P-polarized light) from DMD 605 is transmitted through TIRprism 602 and is irradiated into cross-dichroic prism 608.

On the other hand, the blue light and green light (P-polarized light)that are emitted in time divisions from light source unit 62 areirradiated into TIR prism 604. TIR prism 604 also includes the sameconfiguration as TIR prism 603.

The blue and green light (P-polarized light) that are irradiated fromlight source unit 62 into TIR prism 604 are totally reflected by theinternal total reflection surfaces and are emitted from the secondsurface of the first right-angle prism. The light emitted from thissecond surface is irradiated into DMD 607.

DMD 607 also has the same configuration as DMD 606. A blue image or agreen image is formed by the reflected light (S-polarized light) fromDMD 607. The blue and green light (S-polarized light) from DMD 607 aretransmitted through TIR prism 604 and irradiated into cross-dichroicprism 608.

As shown in FIG. 13, cross-dichroic prism 608 includes four right-angleprisms 209 a-209 d. Right-angle prisms 209 a-209 d are each similar toright-angle prisms 109 a-109 d, respectively, that are shown in FIG. 3,and are provided with an RR surface and BR surface.

The BR surface has the spectral transmission characteristics shown inFIGS. 4A and 4B, and the RR surface has the spectral transmissioncharacteristics shown in FIGS. 4C and 4D.

In cross-dichroic prism 608 shown in FIG. 13, the third surfaces of eachof right-angle prism 209 a, 209 b, and 209 d are the first, second, andthird incident surfaces, respectively, and the third surface ofright-angle prism 209 c is the emission surface.

The red light (S-polarized light) from DMD 606 is irradiated from thefirst incident surface, the green light (P-polarized light) from DMD 605is irradiated from the second incident surface, and the blue light(S-polarized light) and green light (S-polarized light) from DMD 607 areirradiated from the third incident surface.

The red light (S-polarized light) that is irradiated from the firstincident surface is reflected by the RR surface and then emitted fromthe emission surface. The green light (P-polarized light) that isirradiated from the second incident surface is transmitted through theBR surface and the RR surface and then emitted from the emissionsurface. The blue light (S-polarized light) and green light (S-polarizedlight) that are irradiated from the third incident surface are reflectedby the BR surface and then emitted from the emission surface.

Projection lens 610 is arranged on the emission surface side ofcross-dichroic prism 608. The center ray (optical axis) of each lightbeam from light source units 61 and 62 coincides with the optical axisof projection lens 610. Projection lens 610 enlarges and projects theimages that are formed by DMDs 605-607 onto a projection screen.

Each of DMDs 605-607 is provided with an image formation region thatforms an image that is composed of a plurality of picture elements. Thenumbers of picture elements and the sizes of the picture elements ofDMDs 605-607 are identical. However, the relative positional relation ofthe image formation regions on the projection surface differs for DMD607 and DMDs 605 and 606.

More specifically, on the projection surface, the image formation regionof DMD 607 is projected on a position that is shifted by a predeterminedamount in the horizontal direction (the direction of picture elementrows), the vertical direction (the direction of picture element columns)or in both directions with respect to the projected position of theimage formation region of DMD 605. For example, the positional relationof DMDs 605 and 607 is similar to the relative positional relation ofthe image formation regions of display panels 106 and 108 shown in FIG.5. The projected position of image formation region of DMD 606 coincideswith the projected position of the image formation region of DMD 607.

In the present exemplary embodiment as well, a panel arrangement is usedin which the corresponding picture element of an image that is projectedon the projection surface is shifted for DMD 607 and DMD 605 to increasethe number of picture elements of the observed image when the projectedimage is viewed.

More specifically, a green image is formed in DMD 605, a red image isformed in DMD 606, and a blue image and green image are formed in timedivisions in DMD 607. On the projection surface, the green image formedin DMD 607 is projected at a position that is shifted by 0.5 pictureelements in each of the row direction and the column direction withrespect to the projected position of the green image that is formed inDMD 605. Due to the afterimage phenomenon of the human eye, an image(superposed image) is observed in which these green images are spatiallyor temporally blended. The number of picture elements of this observedimage is approximately four times the number of picture elements of eachof DMDs 605 and 607.

The configuration and operation of the control system of the projectorof the present exemplary embodiment are next described in detail.

FIG. 14 shows an example of the control system of the projector of thepresent exemplary embodiment. Referring to FIG. 14, the projectorincludes: light source drive unit 20 that drives light source units 61and 62, panel drive unit 30 that drives DMDs 605-607, input unit 4, andcontrol unit 1 that receives instruction signals from input unit 4 tocontrol the operation of light source drive unit 20 and panel drive unit30. Input unit 4 is the same as the component shown in FIG. 6.

Control unit 1 both supplies drive timing signal S20 for driving each ofDMDs 605-607 to panel drive unit 30 and supplies lighting timing signalS30 for driving each of light source units 61 and 62 to light sourcedrive unit 20.

Panel drive unit 30 individually drives DMDs 605-607 based on videosignal Si that is received as input from an outside device and drivetiming signal S20 from control unit 1. In this case, the outside deviceis an information processing device such as a personal computer or animage apparatus such as a recorder.

More specifically, based on video signal Si and drive timing signal S20,panel drive unit 30 generates image signal S41 that indicates a firstgreen image, image signal S42 that indicates a red image, image signalS43 that indicates a blue image, and image signal S44 that indicates asecond green image. The first green image that is based on image signalS41 is formed in DMD 605, the red image that is based on image signalS42 is formed in DMD 606, and the blue image that is based on imagesignal S43 and the second green image that is based on image signal S44are formed in time divisions in DMD 607.

Light source drive unit 20 individually controls the lighted states oflight source units 61 and 62 in accordance with the lighting timingsignal S3 from control unit 1. More specifically, light source driveunit 20 generates lighting signal S51 that instructs thelighting/extinguishing of light source unit 61 and lighting signal S52that instructs the lighting/extinguishing of light source unit 62.

In light source unit 61, laser 701 lights up, and moreover, phosphorwheel 611 rotates in accordance with lighting signal S51, whereby lightsource unit 61 supplies yellow light.

In light source unit 62, laser 701 lights up, and moreover, phosphorwheel 612 rotates in accordance with lighting signal S52, whereby lightsource unit 62 supplies green light and blue light in time divisions.

In the present exemplary embodiment, image signals S41-S44 are the sameas image signals S21-S24 shown in FIG. 7.

In interval T1, the first green image that is based on image signal S41is formed by DMD 605, the red image that is based on image signal S42 isformed by DMD 606, and the second green image that is based on imagesignal S44 is formed by DMD 607.

In interval T2, the first green image that is based on image signal S41is formed by DMD 605, the red image that is based on image signal S42 isformed by DMD 606, and the blue image that is based on image signal S43is formed by DMD 607.

The operation of supplying green light and blue light in time divisionsin light source unit 62 and the operation of forming the blue image andthe second green image in time divisions in DMD 607 are synchronized.

In interval T1, the first green image that is formed in DMD 605, the redimage that is formed in DMD 606, and the second green image that isformed in DMD 607 are each projected by projection lens 610. In thiscase, a first superposed image in which the first green image, the redimage, and the second green image are superposed is displayed on theprojection surface.

In interval T2, the first green image that is formed in DMD 605, the redimage that is formed in DMD 606, and the blue image that is formed inDMD 607 are each projected by projection lens 610. In this case, asecond superposed image in which the first green image, the red image,and the blue image are superposed is displayed on the projectionsurface.

Due to the afterimage phenomenon, the user observes an image in whichthe first superposed image that is displayed in interval T1 and thesecond superposed image that was displayed in interval T2 are temporallyblended. In this observed image, the second green image is shifted by0.5 picture elements in each of the row direction and the columndirection with respect to the first green image. As a result, the numberof picture elements of the superposed image of the first and secondgreen images is approximately four times the number of picture elementsof each of display panels 106 and 108.

Due to the above-described characteristics of human vision, the numberof picture elements of the green image is increased, whereby the numberof picture elements of the observed image itself appears to beincreased. As a result, higher resolution of the observed image can beachieved.

The projector of the present exemplary embodiment also exhibits the sameaction and effects as the projector of the first exemplary embodiment.

Each of the projectors of the above-described exemplary embodiments areexamples of the present invention, and the configuration and operationare open to appropriate modifications within a scope that does notdepart from the basic idea of the invention.

For example, in the projector of the first exemplary embodiment, therelation of P-polarized light and S-polarized light may be reversed. Inthis case, the spectral transmission characteristics for eachpolarization direction are changed as appropriate for polarization beamsplitters 103-105 and cross-dichroic prism 109.

In addition, although the projector of the first exemplary embodiment isconfigured such that a first green image is formed in display panel 106,a red image is formed in display panel 107, and a blue image and asecond green image are formed in time divisions in display panel 108,the present invention is not limited to this form. The projector of thefirst exemplary embodiment may be configured such that a first greenimage is formed in display panel 106, a red image and second green imageare formed in time divisions in display panel 107, and a blue image isformed in display panel 108.

In the cases described above, the projector is configured in FIG. 1 suchthat red light (P-polarized light) supplied from light source unit 12and green light (P-polarized light) supplied from light source unit 14are irradiated into display panel 107. The spectral transmissioncharacteristics of the BR surface and RR surface of cross-dichroic prism109 are then changed as follows. The characteristics of the BR surfaceare set to characteristics to reflect the blue light (S-polarized light)from display panel 108 and to transmit the green light (P-polarizedlight) from display panel 106 and the red light (S-polarized light) andthe green light (S-polarized light) from display panel 107. On the otherhand, the characteristics of the RR surface are set to characteristicsto transmit the blue light (S-polarized light) from display panel 108and the green light (P-polarized light) from display panel 106 and toreflect the red light (S-polarized light) and the green light(S-polarized light) from display panel 107. In this case, in FIG. 7 orFIG. 8, the ON/OFF relations between lighting signals S32 and S33 aremutually reversed and the ON/OFF relations between image signals S22 andS32 are mutually reversed.

Further, although the second green image is shifted by 0.5 pictureelements in each of the row direction and column direction with respectto the first green image in the projector of the first and secondexemplary embodiments, the picture element shift is not limited to thisamount. The amount of picture element shifting should be set asappropriate within a range of from 0.4 to 0.6 times the picture elementpitch or from 1.4 to 1.6 times the picture element pitch. However, theamount of picture element shift (the ideal value) for reliably obtainingthe effect of increasing the number of picture elements is 0.5 pictureelements.

Finally, although the present invention can assume forms such as shownin SUPPLEMENTARY NOTES 1-10 below, the present invention is not limitedto these forms.

[Supplementary Note 1]

-   A projector comprising:-   first and second display panels that are each equipped with a    plurality of picture elements and that modulate incident light by    means of the plurality of picture elements to form images; and-   projection means that superposes the images that are formed on the    first and second display panels to project the superposed images on    a projection surface;-   wherein the first and second display panels are arranged such that    the image of one of the display panels is projected on a position    that is shifted by a predetermined distance with respect to the    image of the other display panel.

[Supplementary Note 2]

-   In the projector described in SUPPLEMENTARY NOTE 1, the first    display panel forms a first green image, and the second display    panel alternately forms a second green image, in which at least the    luminance differs from the first green image, and a blue or red    image.

[Supplementary Note 3]

-   The projector described in SUPPLEMENTARY NOTE 2 further includes:-   a third display panel that is equipped with a plurality of picture    elements and that modulates incident light by means of the plurality    of picture elements to form an image;-   a first illumination unit that is equipped with a first green light    source that supplies green light, the green light that is supplied    from the first green light source irradiating the first display    panel;-   a second illumination unit that is equipped with a second green    light source that supplies green light and a blue light source that    supplies blue light, the green light that is supplied from the    second green light source and the blue light that is supplied from    the blue light source alternately irradiating the second display    panel; and-   a third illumination unit that is equipped with a red light source    that supplies red light, the red light that is supplied from the red    light source irradiating the third display panel;-   wherein the projection means has:-   a color synthesizing unit that synthesizes the images that are    formed in the first to third display panels; and-   a projection lens that projects the synthesized image that is    synthesized in the color synthesizing unit; and-   wherein the perpendicular line that passes through the center of the    image formation region of each of the first and third display panels    and the perpendicular line that passes through the center of the    image formation region of the second display panel are not in the    same plane.

[Supplementary Note 4]

-   The projector as described in SUPPLEMENTARY NOTE 3 further includes:-   control means that, based on an input video signal, controls the    lighted states of the first and second green light sources, the red    light source, and the blue light source and that causes the first to    third display panels to display images;-   wherein the control means:-   in a first interval, causes lighting of the first green light source    to cause the first display panel to form the first green image,    causes lighting of the second green light source to cause the second    display panel to form the second green image, and causes lighting of    the red light source to cause the third display panel to form the    red image; and-   in a second interval, causes lighting of the first green light    source to cause the first display panel to form the first green    image, causes lighting of the blue light source to cause the second    display panel to form the blue image, and causes lighting of the red    light source to cause the third display panel to form the red image.

[Supplementary Note 5]

-   The projector as described in SUPPLEMENTARY NOTE 3 further includes:-   control means that, based on an input video signal, controls the    lighted states of the first and second green light sources, the red    light source, and the blue light source and that causes the first to    third display panels to form images;-   wherein the control means:-   in a first interval, causes lighting of the first green light source    to cause the first display panel to form the first green image,    causes lighting of the second green light source to cause the second    display panel to form the second green image, and causes lighting of    the red light source to cause the third display panel to form the    red image; and-   in a second interval, causes lighting of the blue light source to    cause the second display panel to form the blue image and causes    lighting of the red light source to cause the third display panel to    form the red image.

[Supplementary Note 6]

-   The projector described in SUPPLEMENTARY NOTE 2 further includes:-   a third display panel that forms an image composed of a plurality of    picture elements;-   a first illumination unit that supplies green light and red light,    the green light irradiating the first display panel and the red    light irradiating the third display panel; and-   a second illumination unit that alternately supplies blue light and    green light, the blue and green light irradiating the second display    panel;-   wherein the projection means has:-   a color synthesizing unit that synthesizes images that are formed by    the first to third display panels and displayed; and-   a projection lens that projects the synthesized image that was    synthesized in the color synthesizing unit;-   wherein the perpendicular line that passes through the center of the    image formation region of each of the first and third display panels    and the perpendicular line that passes through the center of the    image formation region of the second display panel are not in the    same plane.

[Supplementary Note 7]

-   The projector described in SUPPLEMENTARY NOTE 6 further includes:-   control means that, based on an input video signal, controls the    lighted states of the first and second illumination units and causes    the first to third display panels to form the images;-   wherein the control means:-   in a first interval, causes output of each of the green light and    red light from the first illumination unit to both cause the first    display panel to form the first green image and cause the third    display panel to form the red image, and causes output of the green    light from the second illumination unit to cause the second display    panel to form the second green image;-   in a second interval, causes output of each of the green light and    red light from the first illumination unit to both cause the first    display panel to form the first green image and cause the third    display panel to form the red image, and causes output of the blue    light from the second illumination unit to cause the second display    panel to form the blue image.

[Supplementary Note 8]

-   In the projector as described in SUPPLEMENTARY NOTE 6 or 7, wherein    the first illumination unit is provided with:-   a first excitation light source that supplies excitation light;-   a first phosphor wheel in which a yellow phosphor portion that is    excited by the excitation light that is supplied from the first    excitation light source and that emits fluorescent light having an    emission peak wavelength in the yellow wavelength band is formed    along the circumferential direction; and-   a dichroic mirror that separates the fluorescent light emitted from    the yellow phosphor unit into red light and green light;-   the first illumination unit being configured such that the first    phosphor wheel is rotated, the excitation light supplied from the    first excitation light source is irradiated upon the yellow phosphor    portion, and the red light and green light that are separated by the    dichroic mirror are each supplied; and-   the second illumination unit is provided with:-   a second excitation light source that supplies blue light; and-   a second phosphor wheel, in which a green phosphor portion that is    excited by the blue light that is supplied from the second    excitation light source to emit green fluorescent light, and a    transmission portion through which the blue excitation light is    transmitted are formed in predetermined proportions along the    circumferential direction;-   the second illumination unit being configured such that the second    phosphor wheel is rotated, the blue light that is supplied from the    second excitation light source irradiates the green phosphor portion    and the transmission portion, and the green fluorescent light that    is emitted from the green phosphor portion and the blue light from    the second excitation light source that is transmitted through the    transmission portion are alternately supplied.

[Supplementary Note 9]

-   In the projector as described in any one of SUPPLEMENTARY NOTES 1 to    8, the direction of shifting of the image of one display panel with    respect to the image of the other display panel is at least one of    the row direction and the column direction of the array of the    picture elements.

[Supplementary Note 10]

-   An image display method is carried out in a projector that is    provided with first and second display panels that are each equipped    with a plurality of picture elements and that modulate incident    light by means of the plurality of picture elements to form images    and that superposes the images formed by the first and second    display panels to project the superposed images on a projection    surface, the method including:-   arranging the first and second display panels such that the image of    one display panel is projected on a position that is shifted by a    predetermined distance with respect to the image of the other    display panel; and-   forming a first green image on the first display panel, and    alternately forming a second green image, in which at least the    luminance differs from that of the first green image, and a blue    image or red image on the second display panel.

In the projectors described in SUPPLEMENTARY NOTES 1 and 2, the firstand second display panels correspond to display panels 106 and 108 ofthe projector of the first exemplary embodiment (or to DMDs 605 and 607of the projector of the second exemplary embodiment). The projectionmeans corresponds to projection lens 110 and dichroic prism 109 (orprojection lens 610 and dichroic prism 608 of the projector of thesecond exemplary embodiment).

The projector of the above-described SUPPLEMENTARY NOTES 3-5 correspondsto the projector of the first exemplary embodiment. The third displaypanel corresponds to display panel 107. The first illumination unitcorresponds to, for example, light source unit 11 and polarization beamsplitter 103. The second illumination unit corresponds to, for example,light source units 13 and 14, dichroic mirror 102, and polarization beamsplitter 105. The third illumination unit corresponds to, for example,light source unit 12 and polarization beam splitter 104. The controlmeans is realized as a portion of the functions of parts composed ofcontrol unit 1, light source drive unit 2, and panel drive unit 3.

The projector described in SUPPLEMENTARY NOTES 6-8 above corresponds tothe projector of the second exemplary embodiment. The third displaypanel corresponds to DMD 606. The first illumination unit correspondsto, for example, light source unit 61, dichroic mirror 601, retardationplate 609, and TIR 602 and 603. The second illumination unit correspondsto, for example, light source unit 62 and TIR 604. The control means isrealized as a portion of the functions of parts that are composed ofcontrol unit 1, light source drive unit 20, and panel drive unit 30.

1. A projector comprising: first and second display panels that are eachequipped with a plurality of picture elements and that modulate incidentlight by means of said plurality of picture elements to form images; anda projection unit that superposes said images that are formed on saidfirst and second display panels to project the superposed images on aprojection surface; wherein said first and second display panels arearranged such that the image of one of the display panels is projectedon a position that is shifted by a predetermined distance with respectto the image of the other display panel.
 2. The projector as set forthin claim 1, wherein said first display panel forms a first green image,and said second display panel alternately forms a second green image, inwhich at least the luminance differs from said first green image, and ablue or red image.
 3. The projector as set forth in claim 2, furthercomprising: a third display panel that is equipped with a plurality ofpicture elements and that modulates incident light by said plurality ofpicture elements to form an image; a first illumination unit that isequipped with a first green light source that supplies green light, saidgreen light that is supplied from the first green light sourceirradiating said first display panel; a second illumination unit that isequipped with a second green light source that supplies green light anda blue light source that supplies blue light, said green light that issupplied from said second green light source and said blue light that issupplied from said blue light source alternately irradiating said seconddisplay panel; and a third illumination unit that is equipped with a redlight source that supplies red light, said red light that is suppliedfrom said red light source irradiating said third display panel; whereinsaid projection unit comprises: a color synthesizing unit thatsynthesizes said images that are formed in said first to third displaypanels; and a projection lens that projects the synthesized image thatis synthesized in said color synthesizing unit; wherein theperpendicular line that passes through the center of the image formationregion of each of said first and third display panels and theperpendicular line that passes through the center of the image formationregion of said second display panel are not in the same plane.
 4. Theprojector as set forth in claim 3, further comprising: a control unitthat, based on an input video signal, controls the lighted states ofsaid first and second green light sources, red light source, and bluelight source and that causes said first to third display panels todisplay images; wherein said control unit: in a first interval, causeslighting of said first green light source to cause said first displaypanel to form said first green image, causes lighting of said secondgreen light source to cause said second display panel to form saidsecond green image, and causes lighting of said red light source tocause said third display panel to form said red image; and in a secondinterval, causes lighting of said first green light source to cause saidfirst display panel to form said first green image, causes lighting ofsaid blue light source to cause said second display panel to form saidblue image, and causes lighting of said red light source to cause saidthird display panel to form said red image.
 5. The projector as setforth in claim 3, further comprising: a control unit that, based on aninput video signal, controls the lighted states of said first and secondgreen light sources, red light source, and blue light source and thatcauses said first to third display panels to form images; wherein saidcontrol unit: in a first interval, causes lighting of said first greenlight source to cause said first display panel to form said first greenimage, causes lighting of said second green light source to cause saidsecond display panel to form said second green image, and causeslighting of said red light source to cause said third display panel toform said red image; and in a second interval, causes lighting of saidblue light source to cause said second display panel to form said blueimage and causes lighting of said red light source to cause said thirddisplay panel to form said red image.
 6. The projector as set forth inclaim 2, further comprising: a third display panel that is equipped witha plurality of picture elements and that modulates incident light bysaid plurality of picture elements to form an image; a firstillumination unit that supplies green light and red light, the greenlight irradiating said first display panel and the red light irradiatingsaid third display panel; and a second illumination unit thatalternately supplies blue light and green light, the blue and greenlight irradiating said second display panel; wherein said projectionunit comprises: a color synthesizing unit that synthesizes images thatare formed by said first to third display panels; and a projection lensthat projects the synchronized image that was synthesized in said colorsynthesizing unit; and wherein a perpendicular line that passes throughthe center of the image formation region of each of said first and thirddisplay panels and a perpendicular line that passes through the centerof the image formation region of said second display panel are not inthe same plane
 7. The projector as set forth in claim 6, furthercomprising: a control unit that, based on an input video signal,controls the lighted states of said first and second illumination unitsand that causes said first to third display panels to form said images;wherein said control unit: in a first interval, causes output of each ofsaid green light and red light from said first illumination unit to bothcause said first display panel to form said first green image and causesaid third display panel to form said red image, and causes output ofsaid green light from said second illumination unit to cause said seconddisplay panel to form said second green image; in a second interval,causes output of each of said green light and red light from said firstillumination unit to both cause said first display panel to form saidfirst green image and cause said third display panel to form said redimage, and causes output of said blue light from said secondillumination unit to cause said second display panel to form said blueimage.
 8. The projector as set forth in claim 6, wherein: said firstillumination unit is equipped with: a first excitation light source thatsupplies excitation light; a first phosphor wheel in which a yellowphosphor portion that is excited by said excitation light that issupplied from said first excitation light source and emits fluorescentlight having an emission peak wavelength in the yellow wavelength bandis formed along the circumferential direction; and a dichroic mirrorthat separates said fluorescent light emitted from said yellow phosphorunit into red light and green light; said first illumination unit beingconfigured such that said first phosphor wheel is rotated, saidexcitation light supplied from said first excitation light source isirradiated upon said yellow phosphor portion, and said red light andgreen light that are separated by said dichroic mirror are eachsupplied; and said second illumination unit is provided with: a secondexcitation light source that supplies blue light; and a second phosphorwheel, in which a green phosphor portion that is excited by said bluelight that is supplied from said second excitation light source to emitgreen fluorescent light, and a transmission portion through which saidblue excitation light is transmitted are formed in a predetermined ratioalong the circumferential direction; said second illumination unit beingconfigured such that said second phosphor wheel is rotated, said bluelight that is supplied from said second excitation light sourceirradiates said green phosphor portion and said transmission portion,and said green fluorescent light that is emitted from said greenphosphor portion and said blue light from said second excitation lightsource that is transmitted through said transmission portion arealternately supplied.
 9. The projector as set forth in claim 1, whereinthe direction of shifting of the image of said one display panel withrespect to the image of said other display panel is at least one of therow direction and the column direction of the array of said pictureelements.
 10. An image display method that is carried out in a projectorthat is equipped with first and second display panels that are eachequipped with a plurality of picture elements and that modulate incidentlight by said plurality of picture elements to fog n images and thatsuperposes said images formed by said first and second display panels toproject the superposed images on a projection surface, said methodcomprising: arranging said first and second display panels such that theimage of one display panel is projected on a position that is shifted bya predetermined distance with respect to the image of the other displaypanel; and forming a first green image on said first display panel, andalternately forming on said second display panel a second green image,in which at least the luminance differs from that of said first greenimage, and a blue image or a red image.